Electroluminescence device containing a thin film electrode

Abstract

A thin film electrode comprising an electron-injectable metal and an organic compound. Said thin film electrode has excellent uniformity and may be very thin and has a small volume resistivity. An electroluminescence device using said thin film electrode has high luminous efficiency, making it useful as a light-emitting material.

What is claimed: 
     
       1. An electroluminescence device which comprises (a) an anode, (b) a cathode, and disposed between said anode and said cathode (c) an organic emitting layer and (d) optionally a hole-injection layer and (e) optionally an electron-injection layer, said cathode being a thin film electrode comprising film forming amounts of an electron-injectable metal and an organic compound, said device having a structure selected from the group consisting of anode/light emitting layer/cathode, anode/hole-injection layer/light emitting layer/cathode, anode/hole-injection layer/light emitting layer/electron-injection layer/cathode and anode/light emitting layer/electron-injection layer/cathode. 
     
     
       2. The electroluminescence device as defined in claim 1 wherein the weight ratio of the organic compound to the electron injectable metal is 1 to 30% by weight. 
     
     
       3. The electroluminescence device as defined in claim 1 wherein said electron-injectable metal is selected from the group consisting of Mg, Yb, In, Eu, Ce, Er, Hf, Gd, La, Sc, Sm, Y and Zn. 
     
     
       4. The electroluminescence device as defined in claim 1 wherein said organic compound has a property of adhering to or combining with said electron-injectable metal. 
     
     
       5. The electroluminesence device as defined in claim 1 wherein said organic compound has a property of an acceptor. 
     
     
       6. The electroluminescence device as defined in claim 1 wherein said organic compound is represented by the formula. ##STR26## 
     
     
       7. The electroluminescence device as defined in claim 1 wherein said organic compound has a property of forming complexes with an electron-injectable metal. 
     
     
       8. The electroluminescence device as defined in claim 1 wherein said organic compound is nonmetallic phthalocyanine; 5,10,15,20-tetra(4-pyridyl)porphyrin; 5,10,15,20-tetraphenylporphyrin, or 2,3,7,8,12,13,17,18-octaethylporphyrin. 
     
     
       9. The thin film electrode for devices as defined in claim 5 wherein said organic compound is represented by the formula ##STR27## 
     
     
       10. The thin film electrode for devices as defined in claim 7 wherein said organic compound is nonmetallic phthalocyanine; 5,10,15,20-tetra(4-pyridyl)porphyrin; 5,10,15,20-tetraphenylporphyrin, or 2,3,7,8,12,13,17,18-octaethylporphyrin. 
     
     
       11. The electroluminescence device as defined in claim 1 wherein the weight ratio of the organic compound to the electron injectable metal is 1 to 10% by weight. 
     
     
       12. The electroluminescence device as defined in claim 4 wherein said organic compound is of the formula ##STR28## wherein Me is a metal, n is an integer of 1 to 3, and Z is an atom completing a nucleus having at least two condensed aromatic rings. 
     
     
       13. The electroluminescence device as defined in claim 12 wherein Me is a metal selected from the group consisting of lithium, sodium, potassium, magnesium, calcium, boron, aluminum, zinc, gallium and indium. 
     
     
       14. The electroluminescence device as defined in claim 12 wherein said organic compound is selected from the group consisting of tris(8-quinolinol)aluminum, bis(8-quinolinol)magnesium, bis[benzo(f)-8-quinolinol]zinc, bis(2-methyl-8-quinolinolate)aluminum oxide, tris(8-quinolinol)indium, tris(5-methyl-8-quinolinol)-aluminum, 8-quinolinol lithium, tris(5-chloro-8-quinolinol)-gallium, bis-(5-chloro-8-quinolinol)calcium, poly[zinc(II)-bis(8-hydroxy-5-quinolinonyl)methane and dilithium epindolidione. 
     
     
       15. The electroluminescence device as defined in claim 11 wherein the thin film electrode has a thickness of 50 to 300 nm. 
     
     
       16. The electroluminescence device as defined in claim 15 wherein the organic emitting layer has a thickness of 5 nm to 5 μm. 
     
     
       17. The electroluminescence device as defined in claim 1 having the structure: anode/hole-injection layer/light emitting layer/cathode. 
     
     
       18. The electroluminescence device as defined in claim 1 having the structure: anode/hole-injection layer/light emitting layer/electron-injection layer/cathode. 
     
     
       19. The electroluminescence device as defined in claim 1 having the structure: anode/light emitting layer/electron-injection layer/cathode.